Combobox list and Dynarange - show hierachy

I am trying to usa a List combobox with multiple selections as a filter for my dynarange. But I am struggeling to make it work.

What I want is to pick more than one year from a list of years and use the years in the Dynarange that then will show data on lowest level (days). E.g. I will pick 2019 and 2020 in the list and the Dynarange should return 2019-01-01 (1th of Jan 2019), 2019-01-02,…… 2020-12-30, 2020-12-31 – all days in the interval.

I can select multiple values in the list, but only the first year is returned in the Dynarange with all the 365/366 days.

I have made sure the list have multiselection. An my Dynarange looks as shown in the attachement. And tried a lot of different setting in the hierarchy settings, but can not get the result I want. Also tried to do it in the Picklist, but then I need to select all the days to make it work.

the List can select multiple items, but can only pass one value (i.e. first selected element).
I tried it as well with different version, passing it as a variable, a named range, a cell range etc., but it only returns one value, no matter how many are selected in the list.

On top of this, it is unfortunately not possible yet to have a multi-select in a "normal" combobox. This is a requested feature since 2017.

Selecting a range in a date picker as in other BI-frontend software is a requested feature as well.
If you have a support account you can vote for the features: